Published online before print May 21, 2009, doi: 10.1161/ATVBAHA.109.189175
© 2009 American Heart Association, Inc.
Integrative Physiology/Experimental Medicine |
Matrix Metalloproteinase-9 Is Essential for Ischemia-Induced Neovascularization by Modulating Bone Marrow–Derived Endothelial Progenitor Cells
From the Division of Cardiology, Department of Internal Medicine (P.-H.H., T.-C.W., J.-W.C., S.-J.L.), Taipei Veterans General Hospital; the Institute of Clinical Medicine (P.-H.H., H.-Y.T., S.-J.L.); and the Cardiovascular Research Center (P.-H.H., W.-Y.L., T.-C.W., J.-W.C., S.-J.L.), National Yang-Ming University, Taipei, Taiwan; the Department of Cardiovascular Medicine (P.-H.H., M.S.), University of Tokyo Graduate School of Medicine, Tokyo, Japan; the Graduate Institute of Integrated Medicine (Y.-H.C.), College of Chinese Medicine, China Medical University, Taichung, Taiwan; the Division of Cardiology, Department of Internal Medicine (C.-H.W.), Chang Gung Memorial Hospital, Keelung; Chang Gung University College of Medicine, Taoyuan, Taiwan; Institute and Department of Pharmacology (J.-S.C., J.-W.C.), National Yang-Ming University; and the Division of Anesthesiology (F.-Y.L.), Taipei Medical University Hospital and Department of Anesthesiology, School of Medicine (F.-Y.L.), Taipei Medical University, Taipei, Taiwan.
Correspondence to Shing-Jong Lin, MD, PhD, the Division of Cardiology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei, Taiwan. E-mail sjlin{at}vghtpe.gov.tw or jwchen@vghtpe.gov.tw or msata-circ@umin.net
Objective— Both matrix metalloproteinases (MMPs) and endothelial progenitor cells (EPCs) have been implicated in the process of neovascularization. Here we show that the impaired neovascularization in mice lacking MMP-9 is related to a defect in EPC functions in vasculogenesis.
Methods and Results— Hindlimb ischemia surgery was conducted in MMP-9–/– mice and wild-type (MMP-9+/+) mice. Blood flow recovery was markedly impaired in MMP-9–/– mice when compared with that in wild-type mice as determined by laser Doppler imaging. Flow cytometry demonstrated that the number of EPC-like cells (Sca-1+/Flk-1+) in peripheral blood increased in wild-type mice after hindlimb ischemia surgery and exogenous vascular endothelial growth factor stimulation, but not in MMP-9–/– mice. Plasma levels and bone marrow concentrations of soluble Kit-ligand (sKitL) were significantly elevated in wild-type mice in response to tissue ischemia, but not in MMP-9–/– mice. C-kit positive bone marrow cells of MMP-9–/– mice have attenuated adhesion and migration than those isolated from wild-type mice. In in vitro studies, incubation with selective MMP-9 inhibitor suppressed the colony formation, migration, and tube formation capacities of EPC. Transplantation of bone marrow cells from wild-type mice restored collateral flow formation in MMP-9–/– mice.
Conclusions— These findings suggest that MMP-9 deficiency impairs ischemia-induced neovascularization, and these effects may occur through a reduction in releasing the stem cell-active cytokine, and EPC mobilization, migration, and vasculogenesis functions.
Considering the pivotal roles of matrix metalloproteinases (MMPs) and endothelial progenitor cells (EPCs) for vasculogenesis, we hypothesize that the expression of MMP-9 may not only contribute to matrix degradation but may also directly modulate the behaviors and functions of circulating EPCs. In this study, we show the influence of the targeted deletion of the MMP-9 gene on ischemia-induced neovascularization and address the potential mechanistic link between MMP-9 and EPCs.
Key Words: matrix metalloproteinases • endothelial progenitor cells • neovascularization